Category Archives: How To

Loop-On-Ground Antenna Part 3: Tom’s low-noise, low-profile, portable antenna evolves

Loop on Ground Antenna Part 3

(using multiconductor wire)

by TomL

It dawned on me recently, perhaps due to sloppy thinking or unintended distractions, that I never wrote about my modified Loop on Ground (LoG) receive antenna that I use at parks and such. For over a year now, I have been using 3-conductor rotor wire bought cheap at the local hardware store and have wired the conductors in series. Grayhat (Andrew) was the inspiration when he decided to create a folded dipole along the side of his house.

The usual construction of a LoG antenna for shortwave is a single wire of about 60 feet in circumference in order to not go above one wavelength for 20 meter band usage. If you recall, going above one wavelength will start creating weird lobes in the reception pattern. See – Loop-On-Ground Antenna Part 2.

However, I did not like this 19 foot diameter wire on the ground in public parks just waiting to be tripped over. Like, the time when a horse got loose from its owners and almost tripped over my 60 foot wire. I don’t think I would have liked the resulting lawsuit!

So out of fearful necessity I took some leftover RCA 3-conductor rotor wire, about 29 feet of it, and wired a loop with the conductors in series. This gives about 81 feet of total conductive length. But since it is folded onto itself, there is an undetermined loss of resonant length. Callum (M0MCX) of DXCommander fame has experimented and found folded dipoles need three times more length in the folded section to reach resonance, so my loop is probably around 69 feet (electrically). See – Fold the end of a Dipole Back – What’s Happening?.

In the picture below, the black wire with Ring Terminal at the bottom goes all the way around to the other side, soldered to the green wire, which goes around and is soldered to the red wire, which goes around to the Ring Terminal at the top, plus tie-wraps to hold the wires together.

The next picture is how the Wellbrook Medium Aperture preamplifier is connected to the loop with BNC cable that goes to the 12V power injector. I have had this Wellbrook unit for maybe 6+years with no signs of problems. WARNING – do NOT use the Wellbrook preamplifier in the presence of high powered RF energy like your Amateur Radio antenna pumped with 1000 watts from a linear amplifier; the Wellbrook premap might just overload and get damaged! I did use this loop and preamplifier at last year’s 2022 ARRL Field Day and was able to get away with it because we were only using 100 watts per station. Listening to the 9pm 3916-net trivia group was fun but I still needed to keep it away from the transmitting antennas. Continue reading →

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Georges creates an IARU S meter scale for his Belka-DX

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Many thanks to SWLing Post contributor, Georges Ringotte (F6DFZ), who writes:

When I did tests on my Belka-DX, I noticed that the signal level scale was extremely accurate, each mark is 10 dB

I regretted that the manufacturer didn’t use the IARU S meter scale. So I decided to make my own. With RF Gain to the maximum sensitivity, -73 dBm, or S9, is at the 45 mark. I used Front Designer software to make a scale, with 10 dB graduations above S9, and 6db graduations below S9.

Then this scale was printed on water based transfer, 40 mm by 26 mm, when applied on the existing display.

The result is great, and now I have precise readings of signals reports.

That’s brilliant, Georges! Golly..it looks stock when applied to the screen! Thank you for sharing this!

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Tom’s Recommendations: Earbuds and EQ Settings for Shortwave Listening

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Many thanks to SWLing Post contributor, TomL, who shares the following guest post:

Earbuds for Shortwave Listening

by TomL

A few years ago I had bought the discontinued Sennheiser MM 50 earbuds for a cheap price on Amazon to use in my various radios. The portable radios in particular can use more fidelity because of their small, raspy speakers. I also like to listen without bothering others around me who might not want to listen. And earbuds are a LOT more comfortable for my ear lobes than any over-the-ear headphones I have ever used. Furthermore, the old Apple iPhone 4 earbuds were very harsh to listen to. However, a trade-off is that, generally, earbuds are somewhat fragile; one of the two pairs of MM50’s died through mishandling.

I was generally happy with them while listening to Shortwave broadcasters with a mix of news/talk and music. I especially liked them on Mediumwave listening; stations can sound surprisingly good when playing music. Then I tried using these earbuds on my Amateur Radio transceiver, a Kenwood TS-590S. I was impressed how clear they sounded with a lack of distortion, although there was too much bass. Fortunately, Kenwood supplies USB connected software with an TX & RX 18 band EQ (300 Hz spacing, not octaves).

Here is a frequency response chart I found from Reviewed.com for this model:

One of the notable things about these earbuds is the total lack of distortion. Most likely one of the reasons they sound so clear on Shortwave, which has many LOUD audio spikes.

I had not wanted to get Bluetooth earbuds. However, I had recently upgraded my cell phone and NO headphone jacks anymore! So, while I do not use Bluetooth yet for radios, I can see a time in the future to get a Bluetooth transmitter to plug into a radio with a headphone jack. I am reluctant since I do not like having to recharge my earbuds and I put in a lot of radio listening time. Am I supposed to buy two Bluetooth earbuds and swap while charging? Maybe in the future. And also, am I supposed to buy a Bluetooth transmitter for every non-Bluetooth radio I own? Not likely gonna happen.

In the meantime, I ordered cheap wired earbuds from Amazon. I had a $5 credit for trying Prime, so when I saw these Panasonic ErgoFit wired earbuds (RP-HJE120-K) for slightly over $10, I said to myself, “why not?”. Supposedly wildly popular, they are one of the most rated products on all of Amazon with 133,821 ratings/opinions (perhaps Russian bots?!?!?).

Here is a frequency response chart from ThePhonograph.com for these Panasonic earbuds:

You can see comparatively that the bass response in the very good Sennheiser MM50’s is much stronger, being good music earbuds. But for voice articulation, not as much, even though they have no distortion. The Panasonic ErgoFit’s have more modest bass, less of a dip in the lower midrange audio frequencies, and more importantly, has a peak near 2500 Hz and its harmonic 5000 Hz. The highest highs are also modest compared to the Sennheiser model. This general frequency response to “recess” the bass and treble frequencies and peak the 2500 Hz is very useful for voice intelligibility.

As described by the famous speaker-microphone-sound-system maker, Bob Heil relates what he learned from the scientists at Bell Labs many years ago. Speech intelligibility is enhanced when audio is compensated for our natural human hearing. Equalizing below 160 Hz, reducing the 600-900 Hz region, and peaking the 2000-3000 region centered at 2500 Hz will increase intelligibility dramatically. The story goes that Bell Labs was tasked by parent AT&T with finding out why the earliest phones in the 1920’s sounded so muffled and hard to understand. After many experiments, the scientists found the most important frequencies for our ears + brain to comprehend speech. In other words, our ears are not “EQ-flat” like a scientific instrument is. Continue reading →

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Giuseppe experiments with mediumwave loop induction

Giuseppe upcycles and improves a homebrew MW antenna

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Many thanks to SWLing Post contributor, Giuseppe Morlè (IZ0GZW), who shares the following:

Dear Thomas and Friends of SWLing Post …

This is Giuseppe Morlè. As always, I try recycling what I have and improving upon antennas I’ve built in the past. This is one way we radio lovers can experiment. Many years ago, I made an antenna only for medium waves; by adding a circuit, I can now listen to short waves.

I took advantage of a small frame that I recovered from an old commercial FM / AM stereo receiver by removing its coils for medium waves and I wound around it only two coils sufficient to have a frequency range from 3.5 to 18 MHz.

I remember that the antenna in question also receives medium waves as it was born.

I chose this small frame because I wanted everything to be small in order to carry this compact antenna everywhere.

Unlike my other projects for SW and MW, which have a cable that carries the SW signal to the receiver, this time I used the induction that is created around one end of the loop, which I spiraled to get inside the stylus of my Tecsun PL-660 and which then transfers the signal to the receiver.

I did some tests on my balcony the day after a strong storm and I noticed that the propagation was absent but I still wanted to make sure that everything was working.

[Note that you can translate this video into your language via YouTube’s automatic subtitles. Click here to learn how to do this.]

I will keep you updated on other tests on more favorable days of propagation … I still invite you to follow me on my Youtube channel.

I wish everyone a good listening …
73. Giuseppe Morlè iz0gzw.

Many thanks, Giuseppe. I, for one, love all of your homebrewed and recycled antennas. This one is no exception! What a fun project. I love how you use what you have and aren’t afraid to experiment! Thank you for sharing.

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Guest Post: Monitoring Digital Selective Calling (DCS) with YADD

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Many thanks to SWLing Post contributor, Don Moore–noted author, traveler, and DXer–for the following guest post:

Monitoring DSC with YADD

By Don Moore

(The following article was originally published in the April/May 2022 edition of the Great Lakes Monitor, bulletin of the Michigan Association of Radio Enthusiasts. An all-band listening club, MARE publishes a bi-monthly print bulletin and a weekly e-mail loggings tip-sheet. The club also holds regular get-togethers, picnics, and DXpeditions, generally in southeastern Michigan.)

There are dozens if not hundreds of different digital modes used for communication on the MF and HF bands. These aren’t broadcasts you want to listen to unless you like to hear weird tones, beeps, warbles, and grinding noises interspersed with static. Digital modes are for monitoring, not listening. And monitoring them requires having software that does the listening for you and converts the noises into something meaningful – like the ID of the station you’re tuned to. The learning curve to DXing digital utilities can be steep. There are lots of modes to identify and the software can be complicated to learn. Some broadcasts are encrypted so you can’t decode them no matter how hard you try. But the reward is lots of new stations and even new countries that you wouldn’t be able to add to your logbook otherwise.

One of the easiest digital modes to DX is DSC, or Digital Selective Calling. DSC is a defined as “a standard for transmitting pre-defined digital messages.” Look online if you want to understand the technical specifications that specify the values, placement, and spacing of the tones. The result of those specifications is a string of three-digit numbers like this:

125 107 125 106 120 105 120 104 000 120 022 120 041 000 002 022 020 041 108 002 053 020 080 108 006 053 021 080 070 006 118 021 126 070 126 118 126 126 126 126 126 126 126 126 126 126 117 126 112 126 117 117 117 112 109 125 108 125

Each three-digit value represents either a digit or a key word and the positions of the values map to the various fields contained in the message. This message, which was received on 8414.5 kHz, is a test call from the tanker Brook Trout to the coastal station Coruña Radio in Spain. The sender and destination are not identified by name but rather by their nine-digit MMSI (Maritime Mobile Service Identity) numbers – 538006217 for the vessel and 002241022 for the coastal station.

GETTING STARTED WITH DSC

Logging DSC stations requires three pieces of software. First you need a decoder program that turns the noises into numbers and the numbers into meaning. There are several free and commercial options but the most popular one for beginners is YADD – Yet Another DSC Decoder. YADD is free and easy to set up and while YADD can be used by feeding the audio from a traditional radio into your computer, the most common use is with an SDR. That’s what I use and what I will describe here.

Second you need an SDR application and an SDR. I prefer HDSDR for most of my SDR use but I like SDR-Console for digital work. But any SDR program will work if you can feed the audio to a virtual audio cable. And that’s the final thing you need – a virtual audio cable to create a direct audio connection between your SDR application and YADD. There are several different ones available but I recommend VB-Cable. Your first VB-Cable is free and that is all you need to run a single instance of YADD. If you want to expand you can buy up to four more cables from them later. Continue reading →

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How Jake configures SDR# to listen to Encore classical music

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Many thanks to SWLing Post contributor, Jake Brodsky (AB3A), who shares the following guest post:

How I Listen to Encore on Radio Tumbril

Listening to Classical music on shortwave is a challenge. It has loud and soft parts to the music. There may be selective fading. It isn’t a simple thing.

Also, configuring a software defined radio such as the highly configurable SDR# is not trivial. Note to readers: SDR# has been updated a lot recently and the noise reduction features are vastly improved. Kudos to Youssef Touil for all the hard work on this software. He continues to impress me with every update.

So I have some suggestions for those who are interested in listening:

First, get a decent set of over-the-ear headphones. Don’t rely on laptop speakers. They’re usually not designed for audio fidelity.

Set the radio for DSB reception with Lock Carrier and Anti-Fading checked. I also set the bandwidth to cover about 11 kHz or thereabouts.

On the Audio tab I uncheck the Filter Audio option. I’m going to rely on IF filtering to do my work for me.

Next, find an empty channel on the band where you will be listening to the program. Enable the IF Noise Reduction feature, set it to HiFi, and then set the threshold so that the noise floor is reasonably low. If you set the threshold too high, you’ll lose the higher frequency audio and there will be artifacts from the noise floor that I find unpleasant. A little bit of noise reduction is good, but more is not better.

I also enable the IF Filter/notch processing window to handle any stray birdies from switching mode power supplies. However, if not needed, I turn that feature off.

I turn off the AGC. And then I set the volume level to something reasonable, not too loud, not too soft, but just barely able to hear the noise floor.

Then I tune in the program. I was listening to the Sunday Evening (Monday 0200 UTC) broadcast from WRMI on 5950 kHz. There was some fading going back and forth. However, I took the atmospherics in stride, as if it were part of the experience. The broadcast from this evening
ended with the Pastoral Symphony from Beethoven. There were a few fades and there were a few swells, all due to atmospherics as the signal faded to the noise floor and emerged from it. But there was very little distortion. (thanks to the excellent engineers at WRMI).

The experience was actually sublime.

This is why I listen to shortwave broadcasts.

73,

Jake Brodsky, Amateur Radio Station AB3A

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